Too Much Salt Might Harm Kids' Health: Study

MONDAY Sept. 17, 2012 -- Like most adults in the United States, many American children are getting too much salt in their diets, a new study says.

And, as in adults, that extra sodium might be increasing their blood pressure levels, particularly in children above normal weight.

"Sodium intake is positively associated with systolic blood pressure and risk for pre-high blood pressure and high blood pressure among U.S. children and adolescents, and this association may be strong among those who are overweight or obese," wrote researcher Quanhe Yang and colleagues at the U.S. Centers for Disease Control and Prevention.

Systolic blood pressure is the top number in a blood-pressure readout and it represents the force with which blood comes out of the heart to the rest of the body.

Not everyone, however, is convinced that sodium is the only factor raising children's blood pressure.

"This study looked at one nutrient in isolation. There was no emphasis on the quality of the diet," said pediatric dietitian Lauren Graf, of the Children's Hospital at Montefiore in New York City. "A high intake of sodium may be a marker that there are other areas of the diet that aren't so healthy, and it may suggest low intake of other nutrients that lower blood pressure, like calcium, magnesium and potassium."

Results of the study are published in the Sept. 17 issue of the journal Pediatrics.

The latest government dietary guidelines recommend that most Americans not consume more than 2,300 milligrams of sodium daily, although most people would be fine with significantly less sodium. In general, the minimum amount of sodium recommended for most Americans is 1,500 mg daily, according to the guidelines.

Most Americans, however, get well above the recommended limit of sodium each day. High sodium intake and being overweight or obese are known factors that contribute to high blood pressure, according to background information in the study.

The current study included data from a nationally representative sample of U.S. children from 2003 to 2008. The study included more than 6,200 children between the ages of 8 and 18.

All the children provided information on their diet during the previous 24 hours when they began the study, and 91 percent gave information on their diets for a second day in a telephone interview.

Researchers found that the average child and teen consumed nearly 3,400 mg of sodium daily. Sodium intake increased with age, and males consumed more on average than females. Sodium consumption was higher in non-Hispanic whites than in other races.

Normal-weight kids ate the most salt, followed by obese and then overweight kids. The prevalence of overweight and obesity in the study was 37 percent.

Children and teens with higher sodium levels had higher rates of pre-high blood pressure and high blood pressure. The study found that when comparing those with the highest sodium consumption to the lowest, those with the highest had twice the odds of having elevated blood pressure. In overweight and obese children and teens, those with the highest rates had 3.5 times the risk of having pre-high blood pressure or high blood pressure.

As sodium levels increased, so too did blood pressure levels. In overweight and obese children, for example, the lowest sodium group had an average systolic blood pressure of 106.2 mm Hg, while the next group up had 108.8 mm Hg.

As sodium levels increased again, the third group had systolic levels that averaged 109 mm Hg, while the highest consumption group had average systolic levels of 112.8 mm Hg, according to the study.

"It was interesting that for kids who are of normal weight, the sodium intake didn't have as big an impact on blood pressure as it did for children who were overweight and obese," said Dr. Michael Moritz, clinical director of pediatric nephrology at the Children's Hospital of Pittsburgh. "We know that being overweight predisposes you to high blood pressure and sodium can also increase the risk of high blood pressure, but the question is, What happens when they occur in relationship to each other?"

Moritz said it's not yet clear what impact, if any, these slight elevations in blood pressure will have on children's future health.

Graf said it isn't healthy for anyone to consume high levels of sodium in the long-term, and she advises parents to be aware of the amount of sodium in their child's diet but not to focus on it.

Graf recommended staying away from processed foods as much as possible, because they contain a lot of sodium. A surprising source of sodium is bread and bread products, such as bagels. One large plain bagel can contain 700 mg of sodium, Graf said.

She recommended giving your kids more fruits and vegetables and whole-grain foods that haven't been overly processed. "The more you buy fresh foods, the less you have to focus on counting sodium milligrams," she said.

Although the study found an association between salt consumption and higher blood pressure in children, it did not prove a cause-and-effect relationship.